The invention relates to a continuously variable chain-belt transmission with cone-disk pulleys (pairs of conical disks) both at the torque-input side and at the torque-output side, an endless flexible torque-transmitting device (often referred to as a chain belt) as well as a device for damping audible noise that occurs as a side effect of transmitting a torque through the chain-belt transmission.
Several different versions within the category of chain-belt transmissions with conical disks are already known. The endless flexible torque-transmitting devices that are used to transmit a torque from the pair of conical disks at the torque-input side to the pair of conical disks at the torque-output side are, for example, link chains or bands of shear-stressed members that run on the conical disks. The link chains employed for this purpose include force-transfer elements with lateral end surfaces that are in frictional contact with the conical disks, thereby transmitting a torque from the pair of conical disks at the input side through the link chain to the pair of conical disks at the output side.
In an arrangement of this kind, the contact between the pairs of conical disks and the force-transfer elements occurs along a polygonal line, because the individual force-transfer elements are spaced apart from each other along the running direction of the chain. As the link chain runs around the pairs of conical disks, the end surfaces of the force transfer elements one after another enter into contact with the conical disks so that the continuous sequence of impacts of the force-transfer elements against the conical disks produces an acoustical resonance in the conical disks.
Given that each of the pairs of conical disks is arranged on a shaft that serves to transmit the torque, the sonic vibrations are propagated through the shafts, their bearings and the transmission housing to the outside and in the end also to the interior of any vehicle equipped with the known state-of-the-art chain-belt transmission.
To attenuate this kind of transmission noise, secondary measures have been employed until now, which included isolating the transmission housing or the chassis tunnel through coated housing components or isolating floor mats.
Another noise-damping measure, known from DE 197 43 675 A1, consists of shell-like elements arranged at the support areas of the conical disks where the space between the shell-like elements and the conical disks is occupied by a pressure fluid, e.g., by the existing oil that is used in the transmission. The concept of this known transmission also provides for a damping layer, e.g., in the form of a polymer layer between the shell-like element and the conical disk. Thus, the aforementioned known transmission represents an attempt to reduce the generation of noise by lessening the impulse transmitted by the link chain as it enters into contact with the conical disks.